Metals having high thermal conductivity have been widely used as a material for a main body of an electronic device including heat-generating components, chasses, heat sinks, and the like. Metal allows heat to spread quickly to the surrounding environment, thereby protecting electronic components vulnerable to heat from local high temperature. In addition, metals have excellent mechanical strength and processability and are suitable for a heat dissipating material having a complex shape. However, metals have disadvantages of high cost and increase in weight. Accordingly, thermally conductive resins are replacing metals.
As electronic devices are reduced in size and improved in performance, components mounted in the devices are required to be highly integrated. However, such devices frequently suffer from malfunction due to thermal load out of proportion to power output. In addition, it is difficult to quickly dissipate heat due to reduction in thickness and weight of the devices. Typical thermally conductive resins have limitations in solving these problems due to low thermal conductivity.
Conventional thermally conductive resins exhibiting heat dissipating properties have been developed by focusing on selection of fillers having high thermal conductivity. As thermally conductive fillers used to provide thermal conductivity, carbon-based fillers such as graphite and ceramic-based fillers such as aluminum oxide, magnesium oxide, and aluminum nitride are mainly used. It has been proposed to use a proper combination of such fillers, fillers having thermal conductivity in a specific range, or fillers having a specific particle size.
However, when high weight ratios of fillers having high thermal conductivity are simply added to a resin to improve thermal conductivity, a resin composition has poor melt flowability causing deterioration in productivity in manufacture of molded articles. In addition, when an injection molding speed is increased in order to improve productivity of such a resin composition, small products suffer from deterioration in injection moldability and large products are likely to suffer from short shot or deterioration in aesthetics. Further, since molded articles manufactured in this way have poor mechanical properties such as strength due to an excess of thermally conductive fillers, the amount of fillers needs to be limited, thereby making it difficult to sufficiently improve thermal conductivity.
Thus, in order to maximize thermal conductivity while minimizing the amounts of such fillers, it is important to allow a network of fillers to be efficiently formed in a thermally conductive resin. In addition, in order to prevent deterioration in injection moldability even when a large amount of fillers are added, it is important to use a resin having low viscosity. However, since such a resin having low viscosity has low molecular weight and high reactivity between molecular chains, thereby easily causing reaction during extrusion and injection molding, unwanted side effects such as curing reaction can occur.
Japanese Patent Publication No. 2011-038078 (Patent document 1) discloses a thermally conductive resin composition containing a high density polyethylene polymer matrix including fillers, and Korean Patent No. 227,123 (Patent document 2) discloses a polycarbonate resin composition which has good chemical resistance and flowability and exhibits excellent stiffness and impact strength. However, in such resin compositions, specific reinforcing agents are used to prevent reduction in impact strength due to thermally conductive fillers, thus there are problems of deterioration in thermal conductivity and moldability.
Therefore, there is a need for a highly thermally conductive resin which can secure flowability to efficiently form a network of fillers, thereby exhibiting improved mechanical properties such as impact strength and tensile strength and thermal conductivity while securing excellent injection moldability.